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Abstract

Introduction
Many small-store intervention trials have been conducted in the United States
and other countries to improve the food environment and dietary behaviors
associated with chronic disease risk. However, no systematic reviews of the methods and outcomes of these trials
have been published. The objective of this
study was to identify small-store interventions and to determine their impact on
food availability, dietary behaviors,
and psychosocial factors that influence chronic disease risk.

Methods
From May 2009 through September 2010, we used PubMed, web-based searches, and listservs to identify small-store interventions that
met the following criteria: 1) a
focus on small food stores, 2) a completed impact evaluation, and 3)
English-written documentation (peer-reviewed articles or other trial documents).
We initially identified 28 trials; 16 met inclusion criteria and were used for
analysis. We conducted interviews with project staff to obtain additional
information. Reviewers extracted and reported data in a table format to ensure
comparability between data.

Results
Reviewed trials were implemented in rural and urban settings in 6 countries and
primarily targeted low-income racial/ethnic minority populations. Common
intervention strategies included increasing the availability of healthier foods
(particularly produce), point-of-purchase promotions (shelf labels, posters),
and community engagement. Less common strategies included business training and
nutrition education. We found significant effects for increased availability of
healthy foods, improved sales of healthy foods, and improved consumer knowledge
and dietary behaviors.

Conclusion
Trial impact appeared to be linked to the increased provision of both healthy foods
(supply) and health communications designed to increase consumption (demand).

Introduction

Small food stores, which are common in low-income areas with a high
proportion of racial/ethnic minorities (1-8), often have limited healthy options
(5-12) and are associated with overconsumption of high-fat, high-sugar foods
(11-15) and high rates of obesity and chronic disease (16-20). In recent years,
public health practitioners have aimed to improve the food environment and
purchasing patterns in small food stores (21-24), yet studies summarizing these
interventions and their effectiveness are lacking.

Our objective was to identify small-store intervention strategies that
produce significant increases in healthy food access and consumption.
Specifically, we sought to present the design and evaluation components of each
trial, to describe the process indicators (reach, dose, and fidelity) and impact
(at the store and consumer levels) associated with each intervention, and to
suggest potential next steps in research, practice, and policy.

From May 2009 through September 2010, we searched the peer-reviewed literature
and “gray” literature. Only literature after 1990 was considered. Gray
literature included newsletters, published (non–peer reviewed) articles, policy
briefs or reports, published trial materials, and conference presentations.
Using fixed search terms, we first conducted a PubMed search of peer-reviewed
literature to identify small-store intervention trials designed to improve
access to healthy foods. We then posted requests on the Healthy Corner Store
Network (HCSN) listserv, conducted HCSN website searches, reviewed the abstracts
from nutrition and food policy conferences, and consulted with colleagues. We
performed searches using the same methods and fixed search terms every 6 months
during the review period (Box). We looked for trials conducted in the United
States and abroad.

Small stores were defined as having fewer than 10 employees and less than
1,000 square feet of floor space. Corner stores were urban small stores that
were independently owned. Convenience stores were small retailers that were part
of national or regional chains. Gas station stores were retail stores for
servicing motor vehicles that also carried a limited selection of foods and
beverages. Bodegas or tiendas were Hispanic-owned small ethnic-food stores.
Urban areas were defined as census block groups with a total population of at
least 2,500 and an overall density of at least 500 people per square mile. Rural
areas were all territory outside urban areas.

Trial selection

We initially identified 28 trials; 8 were drawn from PubMed. All identified
food-store trials were reviewed for inclusion using the following criteria: 1) a
focus on small food stores (although other food sources such as supermarkets and
restaurants could be part of the study), 2) a completed impact evaluation (eg,
pre-post assessment, use of a comparison group, exposure assessment), and 3)
some form of written documentation (eg, peer-reviewed journal article,
newsletter, other published article, policy brief or report, published trial
materials, or conference presentation) that included a description of all
implemented intervention and evaluation strategies and is written in English.
Sixteen trials met inclusion criteria.

To mitigate bias, we documented the search process and the decisions that
were made for each trial document. Two primary reviewers (P.G., M.R.), working
independently, screened and selected trials. Each eligible trial was
systematically appraised in terms of study design, interventions, outcome
measures, fidelity of the implementation of the interventions, and trial
findings. Disagreements were adjudicated by a secondary independent reviewer (J.G.).

Data extraction and analysis

The 2 primary reviewers independently extracted and analyzed data by
carefully reviewing all documents. The secondary reviewer developed the system
of extracting data and coding variables. Variables, such as store type, were
based on industry definitions. The 2 primary reviewers conducted interrater
reliability assessments to assure consistency in coding. The secondary reviewer
resolved discrepancies noted by the 2 primary reviewers and identified and
adjudicated other discrepancies that might affect reliability and analysis.

Primary reviewers were instructed to extract data for each variable and to
organize data using a trial as the unit of analysis. The data, which were
summarized in 3 tables, were descriptive and comprehensive. These tables were
submitted via e-mail to all trial managers (n = 16) for review and revision. Six
months later, 11 of the 16 trial managers participated in semistructured phone
interviews, which were designed to supplement and verify information on trial
components, evaluations, and results. The remaining 5 trial managers did not
respond to our request for an interview or were no longer involved with the
trial.

After the initial review and follow-up, we created categories and terminology
to provide comparability between extracted data. Primary reviewers extracted and
reported data in accordance with this predetermined structure. The tables were
modified accordingly. The secondary reviewer confirmed data accuracy using
initial review findings, e-mail correspondences, interview transcripts, and
extraction and reporting guidelines.

The analytic approach used to assess the trials was therefore based on the
presence or absence of a standard set of quality criteria (eg, randomization,
use of control groups) and the report of impact at the store and consumer
levels. Meta-analytic techniques were not used, given the heterogeneity of
outcome data, which did not permit the creation of summary estimates of impact.

Twelve trials used in-store signage (eg, shelf labels and posters) for
point-of-purchase promotions. Seven trials, such as the Scottish Grocers
Federation Healthy Living Neighborhood Shop (33), used media outside of the
stores. Zhiwaapenewin Akino’maagewin (40-42) and Baltimore Healthy Stores
(27,28) used educational flyers and promotional giveaways. Two trials, Apache
Healthy Stores (25) and Healthy Bodegas (43-45), also used
diverse multilingual social marketing materials in community venues (eg,
newspapers). Three trials, including the Live Well Colorado Healthy Corner Store
Initiative (46,47), used coupons or vouchers to increase healthy food purchases,
and 7 trials used cooking demonstrations or taste tests to introduce unfamiliar
healthy foods.

Community engagement

A common community engagement strategy (n = 8) was the use of stakeholder
workshops to design and refine interventions. The South Los Angeles Healthy
Eating, Active Communities trial (48,49) used community meetings as a forum to
bring store owners and community members together to discuss intervention
strategies (eg, store-front murals). The San Francisco Good Neighbors Program
(36-39) worked to build relationships between government offices and community
organizations.

Two trials worked to improve the small-store refrigeration system. One
grocery store was stocked with a new energy-efficient refrigerator and used
green materials to improve the store infrastructure (55,56). Another monitored
refrigeration systems to ensure effective use (48,49). Three trials, including
the Scottish Grocers Federation Healthy Living Neighborhood Shop project (33)
and Vida Sana Hoy y Mañana (61,62), emphasized stocking and providing display
stands to sell fresh produce. Four trials moved unhealthy products to the back
of the store and shifted healthier items closer to the point of purchase.

Pricing

Six trials included intervention strategies to reduce the cost of foods or
products related to food procurement at the consumer or store level. Three
trials, Baltimore Healthy Stores (27,28), Have a Heart Paisley (29-31), and
Healthy Eating, Active Communities (48,49) provided coupons or vouchers for
consumer purchases. Healthy Foods Hawai’i (32) and Baltimore Healthy Stores
(27,28) provided cash incentives (ie, gift cards for use with their distributor
or wholesaler) to store owners to purchase healthy foods. One trial, Live Well
Colorado (46,47), provided store loans for business expansion and structural
changes that would encourage the stocking and sale of healthy foods. Outback
Stores (53,54) discounted healthy foods.

Food purchasing patterns (eg, frequency of purchase) were the most commonly
assessed consumer behavioral change (n = 14). Thirteen trials used pre-post
evaluations to assess changes in purchasing behaviors, 5 of which used a
comparison group. Eight trials examined change in diet using pre-post
assessments, 5 of which used a comparison group. A quantitative food frequency
questionnaire served as the primary tool for assessments for those trials. Four
trials, including Vida Sana Hoy y Mañana (61,62), used surveys focused
exclusively on intake of a subset of foods, such as produce.

Consumer impact data were available (in both peer-reviewed and gray
literature) for 10 trials. For 7 trials, consistent increases in food and
health-related knowledge were observed; each of these trials included comparison
groups. Other findings, which varied by trial, included increased recognition of
the availability of healthy foods (Romano’s Grocery Store Renovation [55,56])
and increased intention to buy healthy foods (Healthy Eating, Active Communities
[48,49]). Except for 1 trial, none reported significant changes in
self-efficacy.

Discussion

Our findings indicate consistent improvements across most of the trials in
the availability and sale of healthy foods, the purchase and consumption of
those foods, and consumer knowledge. Most of the trials that showed positive
impact used multipronged strategies (food provision, infrastructure, and health
communication) designed to improve both access to healthy foods (supply) and
consumption of those foods (demand), thus demonstrating the need for combined
environmental and behavioral approaches in small-store interventions.

Several studies have demonstrated that price reductions, through discounts,
coupons, vouchers, and loans, can positively affect consumer demand for and
consumption of healthy foods (22,63,64). Although all of the trials presented in
this review sought to increase access to healthy foods by improving
availability, only 6 sought to increase access by providing cost-related
incentives. Research on increasing consumer demand for healthy foods by
manipulating price is needed.

Limiting the availability of unhealthy food should also be considered. Four
trials implicitly sought to discourage consumption by moving those products to
the back of the store and shifting healthier items closer to the point of
purchase. Only 2 aimed to reduce the availability of unhealthy foods. Three
trials provided business training, which aimed to reduce profit loss associated
with stocking and structural changes and was associated with improved healthy
food availability. A combination of modifications to reduce unhealthy food
stocking and consumption and training to reduce profit loss risks should be
included in future trials and may be a sustainable policy-level approach. These
modifications could be achieved through future mandates or licensing
requirements for healthy food stocking.

Our systematic review indicated several deficiencies in small-store trials.
Most trials assessed impact on store stocking of healthy foods, but many trials
failed to consider sales data, and few examined impact on consumer outcomes,
such as diet and health. No retail food-store trials have shown impact on health
outcomes, such as obesity. The ability to influence health outcomes will require
a more systematic evidenced-based approach to modifying the food environment,
greater use of randomized controlled trials to evaluate program effectiveness
(23), and publication in peer-reviewed literature to communicate findings.

Finally, efforts should be made to translate current small-store intervention
findings into policy. Policies aimed at increasing healthy food availability
have the potential to sustain improved nutrition among low-income populations
(22-23). Such policies may need to account for increased food stamp or trial
restrictions associated pwith the Special Supplemental Nutrition Program for
Women, Infants, and Children (65), zoning or licensing mandates (66), economic
incentives (coupons, produce coolers, tax breaks) (63,64), improved store facade
or layout (63,64), and incentivized partnerships between producers,
manufacturers, and distributors. Long-term multisectoral and multiagency efforts
could address economic development in low-income areas with low food
availability and high rates of obesity and chronic disease.

This systematic review has several limitations. Our findings are more
descriptive than definitive. Because the trials varied widely, we did not
conduct a meta-analysis with summary estimates, which would have provided a more
comprehensive and precise statement of findings. We did not require that trials
included in our review publish data in peer-reviewed journals. Although our
conclusions were drawn largely from peer-reviewed literature, we found support
for them in the gray literature, which we included in this study because of the
dearth of information on small-store interventions in peer-reviewed literature.
As a result, our analysis lacks information on assessment tools, and our impact
analysis lacks summary estimates, P values, and data on consumer
psychosocial and behavioral changes, and we cannot assess the relative impact of
different intervention strategies. Consistent and comparable evaluation data are
lacking for 2 reasons: 1) the field is new and emerging, and 2) many assessed
trials were funded by small nonprofit organizations without the resources to
publish in academic journals. These limitations underscore the need for
standardized evaluation methods for and peer-reviewed articles on small-store
interventions.

We provide the first systematic review of small-store
interventions as a potential approach for addressing the obesity and
diet-related chronic disease epidemics in the United States and internationally.
Many of the findings presented are derived from gray literature, which may
challenge their credibility. Nevertheless, the weight of the evidence supports
the use of this approach to improve small-store stocks and sales of healthy
foods, consumer psychosocial factors, and food purchasing and consumption
behaviors. Further research is needed to determine the best combination of
interventions for small-store trials.

Acknowledgments

This review was supported by a Commissioned Analysis grant from the Robert
Wood Johnson Foundation’s Healthy Eating Research program and by an Innovation
Grant from the Johns Hopkins University Center for a Livable Future.

The Corner Store Initiative. Steps to a Healthier LA New Orleans. http://www.stepsla.org/home2/section/3-153/the-corner-store-initiative/.
Accessed May 3, 2010.

Healthier food options are just around the corner: Steps to a Healthier
New Orleans launches healthy food promotion initiative with 13 local corner
stores. Louisiana Public Health Institute; 2007. http://lphi.org/home2/section/2-158/announcement-archive/view/108/.
Accessed March 11, 2010.

Food and Nutrition Service, US Department of Agriculture. Special
Supplemental Nutrition Program for Women, Infants, and Children (WIC):
miscellaneous vendor-related provisions. Final rule. Fed Regist
2008;73(79):21807-11.

The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions.